A popular meme making the rounds in foreign policy circles goes: What if mayors ruled the world? It is also the title of political theorist Benjamin Barber's latest book, a dissection of nations' inability to tackle large problems such as climate change, and a prescription to turn instead to municipal governments to get stuff done.

Michael Bloomberg has sung a similar cities-are-the-future tune since leaving office in New York. "Mayors are pragmatists, not partisans; innovators, not ideologues," he wrote last year in an editorial. Indeed, the paralysis of Washington and the United Nations has spawned a whole cottage industry of Davos-tested ideas on how to bypass the gridlock of national legislatures and get things done. Think Arizona Sen. John McCain's "League of Democracies" idea from 2007. Barber proposes a kind of global "parliament of mayors."

These ideas might come off as hokey or utopian. To be sure, neologisms such as "glocalism" are nauseating. But let's face it: Nations have grown too large and unwieldy, and cities just might be better at solving tough problems because of their decentralized structures and indifference to sovereign borders.

Innovation, as German sociologist Max Weber pointed out, does not come naturally for large organizations. And national governments are no different.

Freedom to experiment

Mayors oversee a growingly diverse mosaic — roughly half of the world's population now reside in cities — which presents challenges but also allows for some degree of do-it-yourself experimentation. The result is zippy bus-rapid transit systems in Guangzhou, China, and nifty bike-sharing programs in places such as New York.

Cities also tend to be less divided places than nations, which gives mayors more flexibility to experiment with bolder ideas with less fear of being voted out of office. But will cities replace the nation state? Are mayors really going to tackle issues such as climate change when they have potholes to worry about? What's more, there is a big divide between, say, Copenhagen, Denmark, and Lagos, Nigeria.

As more people flock to cities, crime and overcrowded slums could present a more accurate picture than the gated communities of creative types that Bloomberg and others idealize. Indeed, rapid urbanization might foretell a grimmer story, writes military expert David Kilcullen, one where violence is not eradicated but moved from mountainside redoubts to inner-city slums, or what he calls "feral cities."

Nor are mayors the godsend that Bloomberg makes them out to be. For every Cory Booker of Newark or Eric Garcetti of Los Angeles, there is a Rob Ford of Toronto or a Ray Nagin of New Orleans. Mayors can be idiosyncratic, even authoritarian, micromanagers. A case in point is the former mayor of Istanbul and now prime minister of Turkey, Recep Tayyip Erdogan, whose interference with the minutia of city planning continually riles up citizens. Mahmoud Ahmadinejad was mayor of Tehran before becoming president of Iran in 2005.

Tame urban hoopla

There is also something of a teleological aspect to all this urbanization hoopla, one that suggests that man was put on this planet to shop at Whole Foods. "We are living our metropolitan destiny," Barber writes. Maybe. But tell that to the bumpkins on the other half of the planet who till the land and prefer nature to urban noise.

Try watching Werner Herzog's documentary Happy People about hunters living on the Siberian taiga, and tell me that urban life trumps life off-the-grid.

That said, cities are poised to do things better than nations. Because most cities outside of Minnesota do not share borders, they generally do not get into spats over territory. Cities also allow for a more streamlined form of civic participation, empowering the individual at the expense of the multinational. For Congress or the U.N., there is no equivalent to dialing 311 for non-emergency services. In that way, cities are a democratizing force. A central reason that the city states of the Hanseatic League gave way to nations in the 17th century, writes Hendrik Spruyt, was their inability to reduce transaction costs for the merchant class. But the reverse is arguably the case today: Nations are too gridlocked, and it's hurting business.

Cities are also bellwethers of social change. It took New York to prohibit smoking in bars before bans became common practice in Europe's cosmopolitan bistros. Maybe those who think that Bloomberg will run for president should think again. It might one day be considered a rung down the ladder from mayor.

Lionel Beehner, a Ph.D. candidate at Yale, is a member of USA TODAY's Board of Contributors.